Silicon carbide (SiC) has excellent heat resistance and mechanical strength and is physically and chemically stable, thus being widely used as an eco-friendly semiconductor material. In addition, recently, the demand for silicon carbide (SiC) substrates as substrates for electronic devices is increasing.
For a silicon carbide (SiC) wafer, reactive gas serving as a source for silicon (Si) and carbon (C) is supplied onto a wafer to induce chemical reaction, thereby forming a silicon carbide epi layer. In general, chemical vapor deposition (CVD) is commonly used to form a thin film on a wafer.
In particular, SiH4 (silane), C2H4 (ethylene), C3H8 (propane) and the like are used as reactive gases for a silicon carbide wafer and such a deposition process is conducted based on the principle that reactive gas is decomposed at high temperatures, resulting in chemical reaction.
A hydrocarbon compound used as a carbon source is thermally decomposed during high-temperature deposition and the time of exposure to the high temperature process is varied depending on the distance from the point, where the source gas is supplied, to the wafer on which the source gas is deposited, which affects reactivity of the reactive gas deposited on the wafer.
Accordingly, the C/Si value of the silicon carbide epi layer formed on the wafer is changed depending on the position of the wafer, physical properties of the silicon carbide epi wafer are non-uniform and thus performance of the wafer may be disadvantageously deteriorated.